The acting director of the Centers for Disease Control and Prevention has halted the publication of a study demonstrating the effectiveness of COVID-19 vaccines, a move that has ignited accusations of political interference in scientific research. The Department of Health and Human Services confirmed the decision on Thursday.
Study Blocked Over Methodology Dispute
The research, which was slated for release in the agency's Morbidity and Mortality Weekly Report on March 19, was blocked by Jay Bhattacharya, who serves as both director of the National Institutes of Health and acting CDC director. According to HHS spokesperson Andrew Nixon, the manuscript did not pass editorial review due to concerns about its methodology.
“Scientific reports are routinely reviewed at multiple levels to ensure they meet the highest standards before publication,” Nixon said in a statement. “The MMWR’s editorial assessment identified concerns regarding the methodological approach to estimating vaccine effectiveness and the manuscript was not accepted for publication.”
Observational Data Under Fire
At the heart of the dispute is the use of observational data to calculate vaccine effectiveness—specifically, analyzing whether vaccinated individuals who tested positive for COVID-19 were less likely to be hospitalized or visit emergency departments. Bhattacharya argued that such methods can be skewed by factors like prior infection, behavior, and differences in healthcare-seeking patterns.
However, public health experts note that this approach has been a standard tool for assessing vaccines against respiratory viruses for years. The same methodology was used in a flu vaccine study published in the MMWR on March 12, a study that cleared review before Bhattacharya took over as acting director.
An HHS official said Bhattacharya met with the study authors, but they declined to revise their approach. The official emphasized that observational studies of respiratory viruses can be influenced by confounding variables, a point that has been widely accepted in the field.
Political Context Intensifies
The blocked study arrives amid a broader Trump administration effort to downplay the vaccine skepticism of HHS Secretary Robert F. Kennedy Jr., who has called the COVID-19 shot “the deadliest vaccine ever made.” Last year, Kennedy announced the CDC would no longer recommend the vaccine for pregnant women and healthy children, a position at odds with mainstream public health guidance.
The CDC has been without a permanent director since Susan Monarez was fired last August after clashing with Kennedy over vaccine policy. President Trump recently nominated Dr. Erica Schwartz as his third pick to lead the agency.
Senator Demands Answers
Sen. Richard Blumenthal (D-Conn.) sent a letter to Bhattacharya on Thursday, accusing him of politicizing science. Blumenthal demanded documents detailing the CDC’s scientific review process, including a list of all studies that have cleared internal review but remain unpublished since the start of the Trump administration.
The controversy echoes broader tensions over vaccine policy within the administration. Meanwhile, a recent report on CDC leadership blocking vaccine effectiveness reports has drawn attention to the agency's internal struggles. As the midterm elections approach, the block is likely to fuel further debate about the role of politics in public health decisions.
